Adjustable leg system

ABSTRACT

Telescoping legs having outer and inner leg members increases stability of an adjustable worktable. The outer leg member has a tubular cross section of a geometric shape to accommodate the cross section of the inner leg member so that the inner leg member fits into the outer leg member. The assembly includes one or more sets of one or more protrusions inwardly projecting from the interior surface of the outer leg member to guide the inner leg member into the outer leg member. In their locations, the protrusions serve to further minimize the gap between the outer leg member and the inner leg member of the telescoping leg assemblies, thereby further improving the stability of the adjustable table. The protrusions are made by crimping, forming, additional hardware, or through other procedures.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to adjustable worktables, and more particularly, to apparatuses and methods for guiding a telescoping table leg during the height adjustment process, and providing further stabilization to the leg assembly.

[0003] 2. Description of the Related Art

[0004] There are various methods with which to adjust the vertical height of a table. One such method is through the use of telescoping legs. When telescoping legs are used, each table leg usually consists of an outer leg member and an inner leg member, with the outer leg member having a slightly larger cross section than the inner leg member, thereby allowing the inner leg member to move longitudinally either up or down within the inner wall of the outer leg member, in order to obtain the desired table height.

[0005] The problem encountered with the use of telescoping legs however, is that the stability of the table can be compromised when there is too much of a gap between the inner wall of the outer leg member and the outer wall of the inner leg member of each telescoping leg assembly. In addition, when the smaller inner leg member is inserted into the inner wall of the larger outer leg member, the two leg members are often difficult to align. Many times, the sliding action of the inner leg member will encounter greater friction due to burrs or other obstacles residing on the inner surface of the outer leg member. When the outer surface of the inner leg member comes into contact with such an obstacle, its ability to slide within the outer leg member is not only hindered, but sometimes jams and remains stuck in a misaligned position. Pulling the two members apart after such an occurrence requires great force, and upon final release, the resulting breakaway force can cause hand and other injuries.

[0006] Thus, an adjustable table with an improved design to increase stability and guide the inner leg member into the outer leg member of a telescoping leg assembly is desired.

BRIEF SUMMARY OF THE INVENTION

[0007] The present invention resides in an adjustable leg system. Embodiments include a worktable or the like of the type having a plurality of generally upright support legs. Each leg includes first and second members. The first member has a tubing with an inner surface having a regular geometric cross-sectional shape to form an outer leg member. The second member has an elongated member with an outer wall having the same geometric cross-sectional shape and of a size smaller than that of the inner surface of the first member to form an inner leg member. The second member is receivable within the first member to form a telescoping leg structure. The inner surface of the outer leg member includes a pair of longitudinally spaced portions which project inwardly to closely receive the outer wall of the inner leg member to guide its longitudinal movements within the outer leg member.

[0008] Other embodiments include for a portion of an article of furniture, a plurality of adjustable legs, each of the adjustable legs includes a first longitudinal member and a second longitudinal member. The first longitudinal member has first and second ends and a length therebetween. The first end is configured for attachment to the portion of the article of furniture. From the second end along at least part of the length, the first longitudinal member is hollow having an interior being accessible through the second end. The interior of the first longitudinal member has an interior surface, an interior longitudinal length and an interior cross-sectional profile taken perpendicular to the interior longitudinal length. The interior cross-sectional profile has a cross-sectional area dependant upon position from the second end along the interior longitudinal length. The cross-sectional area for one or more first sections of the interior is greater than the cross-sectional area for one or more second sections of the interior. The one or more first sections of the interior has a combined longitudinal length greater than 95% of the interior longitudinal length. The second longitudinal member has first and second ends and a longitudinal length and a cross-sectional profile taken perpendicular to the longitudinal length along at least a portion of the longitudinal length from the first end. The cross-sectional profile has a cross-sectional area smaller than the cross-sectional area of the one or more second sections of the interior of the first longitudinal member.

[0009] Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0010]FIG. 1 is an isometric view of an exemplary implementation of an adjustable worktable with telescoping leg assembly.

[0011]FIG. 2 is a cross section of one of the telescoping leg assemblies of the adjustable worktable shown in FIG. 1 taken along the line 2-2.

[0012]FIG. 3 is a cross section of one of the telescoping leg assemblies of the adjustable worktable shown in FIG. 1 taken along the line 3-3.

[0013]FIG. 4 is a elevational side view of the adjustable worktable shown in FIG. 1.

[0014]FIG. 5 is an enlarged cross sectional view of the plunger assembly shown in FIG. 4.

[0015]FIG. 6 is an exploded view of the inner leg member of the adjustable worktable shown in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

[0016] An apparatus is provided for increasing the stability of an adjustable worktable having telescoping legs. The apparatus also serves to guide the inner leg member of each telescoping leg assembly into the outer leg member of the assembly. The outer leg member is hollow with an interior cross-sectional profile generally to accommodate insertion of the inner leg member into the outer leg member while leaving a general gap between the outer and inner leg members to address conventional problems such as binding between the outer and inner leg members.

[0017] The apparatus provides one or more projections or protrusions located on the inner surface of the outer leg member to reduce the interior cross-sectional profile of the outer leg member at these protrusion locations such that the general gap between the outer and inner leg members is reduced to provide guidance for movement of the inner leg member inside the outer leg member during table height adjustment and stability between the leg members once a desired height has been secured. Methods for producing the protrusions on the inner surface of the outer leg member include crimping the outer surface of the outer leg member inwardly, inserting a sleeve to the inner surface of the outer leg member, and molding the outer leg member.

[0018] Accordingly, a worktable or the like has telescoping leg assemblies for table height adjustment. The telescoping leg assemblies include an outer leg member and an inner leg member, which telescope relative to each other. In particular, the design improves the guidance for movement of the inner leg member of each telescoping leg within the outer leg member, and provides greater overall stability to the worktable once each telescoping leg assembly is adjusted to its desired height, as described in detail below. In the following description, numerous specific details are set forth, such as example configurations, etc., to provide an understanding of the invention. One skilled in the art will readily recognize that the invention can be practiced without one or more of the specific details, or may be practiced to adjust the height of other tables, workbenches, or the like. Well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0019] An exemplary implementation of the telescoping leg assembly as incorporated into an adjustable worktable 10 having telescoping legs 12 is shown in FIG. 1. In this exemplary implementation, the telescoping legs 12 are made of malleable metal tubing, rectangular in shape, but in other implementations can be formed in other geometric shapes using other materials such as hard plastic or a composite. Each of the telescoping legs 12 are comprised of a hollow outer leg member 14 separate from an inner leg member 16 that can be either solid or hollow. The outer leg member 14 has a slightly larger interior cross section of its hollow area than the overall cross section of the inner leg member 16 to allow the inner leg member to move inside the interior of the outer leg member.

[0020] For the exemplary implementation, each of the four exterior longitudinal surfaces of each of the outer leg members 14 has two indentations 17 all equally spaced and positioned to form two sets 17′ of indentations per outer leg member. Each set 17′ of indentations 17 result in the forming of a corresponding set 18′ of four inward protrusions 18 on the interior surface of each of the outer leg members 14.

[0021]FIG. 2 depicts a cross section of one of the telescoping legs 12 shown in FIG. 1 along the line 2-2 having the inner leg member 16 inserted into the outer leg member 14 to form the telescoping leg showing two opposite facing of the protrusions 18 for each of the two sets 18′ of protrusions and the related two of the indentations 17 for each of the two corresponding sets 17′ of indentations. The inward protrusions 18 provide guidance and stability for the inner leg member 16 in its sliding/telescoping action within the outer leg member 14. Although the exemplary implementation used a crimping procedure to form the indentations 17, which result in the protrusions 18, other implementations can form the protrusions in other ways such as through a molding procedure in which the indentations 17 are not formed and as a result are not present. Also, the exemplary implementation had four of the protrusions 18 for each of the sets 18′ of protrusions used. In other implementations, fewer or greater numbers of protrusions are possible for each set 18′ of protrusions such as one, two, three, or more protrusions per set depending upon the geometries involved. In a particular set 18′, the protrusions 18 can be continuous with one another to form a protruding region or can be distinctly shaped to appear as a series of protrusions.

[0022] Generally, an implementation will have at least one location on the outer leg member 14 where the interior cross sectional area of the outer leg member is decreased over a relatively short longitudinal length of the outer leg member, which is specifically exemplified by each of the sets 18′ of protrusions. This decrease in interior cross sectional area of the outer leg member 14 for the relatively short longitudinal length can be accomplish in a variety of ways other than the depicted implementation such as forming (as discussed), welding, or additional hardware affixed to interior surfaces of the outer leg member. For instance, some implementations use a sleeve placed in the interior surface of the outer leg member 14.

[0023] Regardless of the manner in which the inward projection of the protrusions 18 is achieved, although in the depicted embodiment the protrusions project inwardly around the entire inner circumference of sections of the interior surface of the outer leg member 14, in other implementations the protrusions do not extend around the entire circumference of interior surface sections, but instead are placed on portions of the interior surface sections. The relatively short longitudinal length for a location of decrease in interior cross sectional area is typically on the order of less than five percent of the total longitudinal length of the outer leg member, and could be on the order of two percent, one percent or less, and in other cases more than the five percent, such as ten percent, but typically does not exceed a substantial portion of the longitudinal length of the outer leg member to avoid problems of the prior art such as binding. As mentioned the protrusions 18 in particular and more generally the reduction of the interior cross-sectional area of the outer leg member over one or more relatively short longitudinal lengths of the outer leg member improves the stability of each leg and the overall stability of the worktable 10 once the position of the telescoping legs 12 is set.

[0024] As stated, the protrusions 18 project inwardly to effectively reduce the interior cross section of the outer leg member 14. In the depicted implementation, the protrusions 18 project inwardly around substantially the entire circumference of a portion of the inner surface of the outer leg member 14, so that the inner leg member 16 is closely received within the outer leg member 14. One way of achieving this result is by crimping the outer surface of the outer leg member 14 inwardly.

[0025] From this cross sectional view, it can be seen that once the inner leg member 16 is inserted into the outer leg member 14, there is a small gap 26 between the inner wall 22 of the outer leg member 14 and the outer wall 24 of the inner leg member 16. However, in each location where one of the protrusions 18 exists, the gap 26 is further reduced. By further reducing the gap 26, the protrusions 18 serve to more securely retain and better stabilize the inner leg member 16 inside the outer leg member 14. An equally important advantage served by the protrusions 18, is that the inner leg member 16 is better guided into the outer leg member 14 during the assembly and adjustment process. As is further discussed below, this guidance function is an important aspect of the invention.

[0026]FIG. 3 shows a cross section of one of the telescoping legs 12 shown in FIG. 1 along the 3-3 line in which the telescoping leg has a rectangular cross-sectional profile. As discussed above, the telescoping leg 12 can have a cross-sectional profile of any geometric shape. Furthermore, the depicted implementation shows two sets 18′ of protrusions 18 for each telescoping leg 12, the sets being spaced six to seven inches apart. It has been found that for a typical worktable with a working surface thirty-five to forty-two inches above the floor, a total of two sets 18′ of protrusions 18 will provide improved stability. Other implementations of the telescoping leg 12 use other spacing between sets 18′ of protrusions 18 or other numbers of sets. In one implementation, for each of the telescoping legs 12, a first of the sets 18′ of the protrusions 18 is located one and a half to three inches from the bottom of the outer leg member 14, and a second of the sets of protrusions is located six to seven inches further up from the first set. The use of protrusions 18 are applied in other implementations to other adjustable tables or other furniture such as adjustable chairs or benches having higher or lower heights and if additional stability is desired additional sets 18′ of the protrusions can be used.

[0027] To lock-in the height of the adjustable worktable, the depicted implementation also has a plunger assembly or releasable latch mechanism 28 mounted to the outer leg member 14, as shown in FIG. 4. This plunger assembly 28 is used to secure the inner leg member 16 to the outer leg member 14. As shown in FIG. 5, the plunger assembly 28 is comprised of a ring 30, a spring or biasing member 32, and a shaft or transverse pin 34. When the plunger assembly 28 is in a static position, the shaft 34 is in a permanently extended position. However, when the ring 30 of the plunger assembly 28 is pulled in a direction opposing the shaft 34, the spring 32 causes the shaft 34 to retract.

[0028] The plunger assembly 28 is mounted to the outer leg member 16 and, for greater table stability, is preferably positioned between the two sets 18′ of protrusions 18 on each outer leg member shown in FIG. 4. Each of the inner leg members 16, as shown for one inner leg member in FIG. 6, has a series of holes or indentations 36 running along the longitudinal axis. To adjust the height of the worktable, the plunger ring 30 is pulled to retract the shaft 34, allowing the inner leg member 16 to be guided by the protrusions 18 into the outer leg member 14. With the ring 30 still pulled, the inner leg member 16 is free to vertically move upwardly or downwardly into the outer leg member 14. When the desired table height is determined, the holes or indentions 36 are aligned on the inner leg member 16 with the plunger assembly 28. Once this is done and the ring 30 is released, the shaft 34 will extend into the hole or indention 36 of the inner leg member 16. This insertion of the shaft 34 into the hole or indention 36, together with the inwardly projecting segments 18, will firmly stabilize and secure each of the telescoping legs 12. Once each of the telescoping legs 12 is adjusted and secured in such a manner, the overall process will result in an adjustable table 10 which is firmly stabilized and supported at the desired height.

[0029] In addition to enhancing the stabilization of the worktable, the protrusions 18 also serve to guide the inner leg member 16 into the outer leg member 14. This enhanced guidance is of great value during table assembly and height adjustment. When the plunger assembly 28 is welded to the outer leg member 14, a welding bead is formed on the inner surface of the outer leg member. Without the use of the protrusions 18 to guide the insertion of the inner leg member 16 into the outer leg member 14, the welding bead on the inner surface of the outer leg member often causes the inner leg member to catch or resist assembly into the outer leg member. Further, the lack of guidance provided by the protrusions 18 often causes the inner leg member 16 to enter askew and as a result of the beading on the inner surface, creates a situation where the misaligned entry of the inner leg member remains stuck in the misaligned position. When this occurs, a large amount of opposing force is required to pull the outer leg member 14 apart from the inner leg member 16. The resulting breakaway force is equally large and can cause hand injury or other unexpected results, such as a loss of balance or elbow injury to the person applying the force.

[0030] The weld bead reviewed above is just one such obstacle that can make inserting the inner leg member 16 into the outer leg member 14 difficult. Often times, the inner surface of the outer leg member 14 will contain rough spots that increase the sliding friction which results when the inner leg assembly 16 is inserted into the outer leg member 14. This increased friction also causes the telescoping leg 12 to misalign and become stuck in an unwanted position. The use of the protrusions 18 on the inner surface of the outer leg member 14 can avoid such situations. Thus, in addition to providing added stability to the telescoping legs 12 of the worktable 10, the protrusions 18 also avoid misalignment as explained.

[0031] From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. For instance, in some implementations the inner leg member 16 may contain protrusions similar to those described for the outer leg member 18 whereas in some of these implementations the outer leg member does not have any protrusions whereas in other of these implementations the outer leg member has other protrusions along with the inner leg member protrusions. Accordingly, the invention is not limited except as by the appended claims. 

1. A worktable or the like of the type having a plurality of generally upright support legs wherein a leg comprises: a first member comprised of tubing having an inner surface having a regular geometric cross-sectional shape to form an outer leg member; a second member comprising an elongated member having an outer wall having the same geometric cross-sectional shape and of a size smaller than that of the inner surface of the first member to form an inner leg member, and wherein the second member is receivable within the first member to form a telescoping leg structure; wherein the inner surface of the outer leg member includes a pair of longitudinally spaced portions which project inwardly to closely receive the outer wall of the inner leg member to guide its longitudinal movements within the outer leg member.
 2. A worktable or the like, as claimed in claim 1, wherein the longitudinally spaced portions comprise projections which project inwardly around substantially the entire interior surface of the outer leg member.
 3. A worktable or the like, as claimed in claim 1, wherein the longitudinally spaced portions comprise projections which project inwardly around a portion of the entire interior surface of the outer leg member.
 4. A worktable or the like, as claimed in claim 3: wherein the-first member comprises malleable metal tubing having a rectangular cross-section to form an outer leg member; and wherein the second member has a rectangular outer cross-sectional shape to form a rectangular inner leg member; and wherein the projections on the interior surface of the outer leg member are formed by crimping the lateral walls of the malleable tubing so that the inner surface of the outer leg member closely receives the inner leg.
 5. A worktable or the like, as claimed in claim 4: wherein all four lateral walls of the outer malleable tubing leg member are crimped at a plurality of vertically spaced intervals to form projections which project inwardly around substantially the entire interior surface of the outer leg member to cause the inner surface of the outer leg member to closely receive the inner leg member and to space the outer walls of the inner leg member substantially uniformly from the inner walls of the outer leg member and to hold the inner leg member in alignment with the outer leg member.
 6. A worktable or the like, as claimed in claim 1, further comprising a releasable latch mechanism for securing the second member to the first member to prevent relative movement and to permit adjustment of the length of the leg structure.
 7. A worktable or the like, as claimed in claim 4: wherein the outer leg member has a hole through its wall; wherein the releasable latch mechanism comprise a transverse pin mounted on the outer leg member for transverse movement through the hole in the wall of the outer leg member and a biasing mechanism for urging the pin inwardly; and wherein the inner leg member includes a plurality of vertically aligned holes for receiving the latch mechanism pin in order to permit the length of the leg structure to be selectively adjusted.
 8. A worktable or the like, of the type having a plurality of generally upright support legs wherein a leg comprises: a first member forming an outer leg member comprised of malleable metal tubing having an inner surface having a regular geometric cross-sectional shape with at least one substantially flat wall; a second member forming an inner leg member having an outer wall having the same geometric cross-sectional shape and of a size smaller than that of the inner surface of the outer leg member with at least one substantially flat wall in juxtaposition with the flat wall of the outer tubing, and wherein the inner leg member is receivable within the outer leg member to form a telescoping leg structure; wherein the inner surface of the outer leg member includes a pair of longitudinally spaced portions which are formed by crimping the lateral walls of the malleable tubing so that the inner surface of outer leg closely receives the inner leg to space the outer walls of the inner leg substantially uniformly from the inner walls of the outer leg and to hold the inner leg member in alignment with the outer leg member; further comprising a releasable latch mechanism for securing the inner leg to the outer leg to prevent relative movement and to permit adjustment of the height of the length of the leg structure; wherein the outer leg member has a hole through its wall; wherein the releasable latch mechanism comprises a transverse pin mounted on the outer leg member for transverse movement through the hole in the wall of the outer leg member intermediate to the two crimped portions; and a biasing mechanism for urging the pin inwardly; and wherein the inner leg member includes a plurality of vertically aligned holes for receiving the latch mechanism pin in order to permit the length of the leg structure to be selectively adjusted and to further secure the inner leg within the outer leg.
 9. A worktable or the like, as claimed in claim 8, wherein the legs are rectangular in cross-section.
 10. A worktable or the like, as claimed in claim 9, wherein the inner and outer leg members are of rectangular metal tubing.
 11. For a portion of an article of furniture, a plurality of adjustable legs, each of the adjustable legs comprising: a first longitudinal member having first and second ends and a length therebetween, the first end configured for attachment to the portion of the article of furniture, from the second end along at least part of the length the first longitudinal member being hollow having an interior being accessible through the second end, the interior having an interior surface, an interior longitudinal length and an interior cross-sectional profile taken perpendicular to the interior longitudinal length, the interior cross-sectional profile having a cross-sectional area dependant upon position from the second end along the interior longitudinal length, the cross-sectional area for one or more first sections of the interior being greater than the cross-sectional area for one or more second sections of the interior, the one or more first sections of the interior having a combined longitudinal length greater than 95% of the interior longitudinal length; and a second longitudinal member with first and second ends and a longitudinal length and a cross-sectional profile taken perpendicular to the longitudinal length along at least a portion of the longitudinal length from the first end, the cross-sectional profile having a cross-sectional area smaller than the cross-sectional area of the one or more second sections of the interior of the first longitudinal member.
 12. The adjustable legs of claim 11 wherein the first longitudinal member has the one or more first sections of the interior with a combined longitudinal length greater than 98% of the interior longitudinal length.
 13. The adjustable legs of claim 11 wherein the first longitudinal member has the one or more first sections of the interior with a combined longitudinal length greater than 99% of the interior longitudinal length.
 14. For a table, a plurality of adjustable legs, each of the adjustable legs comprising: an outer leg member having a length and an open end, the outer leg member being hollow along at least a portion of the length from the open end having an interior accessible through the open end, the interior having interior walls each having a surface, the interior walls having a total surface area and having protrusions extending from one or more of the interior wall surfaces into the interior, the protrusions extending from less than ten percent of the total surface area of the interior walls; and an inner leg member having a length and a cross-sectional profile taken perpendicular to the length along at least a portion of the length, the cross-sectional profile shaped to fit into the open end of the outer leg member and into the interior of the outer leg member including areas of the interior having the protrusions.
 15. The adjustable legs of claim 14 wherein the outer leg member has the protrusions extending from less than five percent of the total surface area of the interior walls.
 16. The adjustable legs of claim 14 wherein the outer leg member has the protrusions extending from less than two percent of the total surface area of the interior walls.
 17. The adjustable legs of claim 14 wherein the outer leg member has the protrusions extending from less than one percent of the total surface area of the interior walls.
 18. For an article of furniture, an adjustable leg comprising: an inner leg member having a length, one or more external walls with external surfaces, and protrusions extending from the external wall surfaces, the protrusions extending from less than ten percent of the total surface area of the external wall surfaces; and an outer leg member having a length and an open end, the outer leg member being hollow along at least a portion of the length from the open end having an interior accessible through the open end, the interior having a cross-sectional profile taken perpendicular to the length along at least a portion of the length, the cross-sectional profile shaped to receive the inner leg member including the protrusions of the inner leg member.
 19. The adjustable leg of claim 18 wherein the inner leg member has the protrusions extending from less than five percent of the total surface area of the external wall surfaces.
 20. The adjustable leg of claim 18 wherein the inner leg member has the protrusions extending from less than two percent of the total surface area of the external wall surfaces.
 21. The adjustable leg of claim 18 wherein the inner leg member has the protrusions extending from less than one percent of the total surface area of the external wall surfaces. 